Electromagnetic actuators and electromagnetic valves which are used as inlet valves for high-pressure fuel pumps within fuel injection systems, for example, are known from DE 10 2011 090 006 A1, for example.
The flow rate of the high-pressure fuel pump at an interface between a low-pressure region and a high-pressure region of a fuel injection system, for example on a high-pressure fuel pump, is regulated by way of a digitally actuated, in particular electromagnetic, valve, for example. This electromagnetic valve is opened or closed, respectively, with the aid of an electromagnet. To this end, the electromagnetic valve has a pole piece and an armature which by way of the electromagnet are moved relative to one another. A defined air gap for the dimensioning of the magnet is present between the armature and the pole piece. In a relative mutual movement of the armature and the pole piece, this gap is overcome such that a stop face that is disposed on the armature and faces the pole piece, and a counter stop face that is disposed on the pole piece and faces the armature is opposite the stop face, impact one another. When the electromagnetic valve is switched on account thereof, oscillations which are emitted as sound by way of the adjacent parts, for example parts of the high-pressure fuel pump, are generated by the impulse which the respective moving part induces in rigid, travel-limiting parts. This is perceived as a disturbing noise. Not only are loud operating noises caused in the mutual impact of the mutually opposite stop face and counter stop face, but the impact can additionally also lead to the mutually impacting faces being damaged, in particular in the case of electromagnetic valves having rapid closing velocities. As a consequence, the service life or the operational life, respectively, of the electromagnetic valves is limited in certain circumstances, and the electromagnetic valves have to be checked or replaced at relatively short intervals.
For example, it is known for the impact of the armature and the pole piece to be reduced by software-based solutions in that the energizing of the electromagnet is prematurely reduced or even switched off, or a counter voltage is applied in order for the armature to be decelerated, respectively.
It is known from DE 10 2012 214 910 A1, for example, to provide a damping layer which damps the impact of the armature and the pole piece.
Additionally, it is known from DE 10 2013 219 439 A1, for example, for the impulse of the impact to be reduced as the armature moves out.